1. Field of the Invention
This invention relates to a graphene and a method for producing the same, more particularly to a chemically-modified graphene and a method for producing the same.
2. Description of the Related Art
Graphene has a single layer of carbon atoms that are densely packed in a two-dimensional honeycomb lattice. Graphene has application potential in the fields of transparent electrodes, thermal interface material, and electrochromic devices because of excellent electrically conductive and thermally conductive properties thereof.
I. L. Aksay et. al. disclosed a method for producing a graphene (Chem. Mater., 19, 4396-4404, 2007). The method involves thermal expansion of a graphite oxide by heating the graphite oxide to a temperature of 1050° C. to generate carbon dioxide by which the graphite oxide is exfoliated to form the graphene.
M. C. Hsiao et. al. disclosed a method for producing a carboxylic acid-containing graphene (ASC Appl. Mater. Interfaces, 2, 3092-3099, 2010). The method involves subjecting an amine-terminated polyetheramine derivate and an epoxy group on a graphene oxide to a ring-opening grafting reaction for 24 hours to form a carboxylic acid-containing graphene derivate. However, in this method, graphite has to be oxidized to form graphite oxide before the carboxylation reaction is conducted, which is time-consuming.
E. K. Choi et. al. disclosed a method for producing an amino group-containing graphene (Chem. Commun., 46, 6320-6322, 2010). The method involves exfoliation of graphite by grafting 4-aminobenzoic acid to defect sites of the graphite in poly(phosphoric acid) (PPA)/phosphorus pentoxide medium. However, because PPA has high viscosity, the grafting reaction is liable to be suppressed. Therefore, a longer reaction time and a subsequent purification step are required.